Field-emission displays are considered an attractive alternative and replacement for liquid-crystal displays, because of their lower manufacturing cost and lower complexity, lower power consumption, higher brightness, and improved range of viewing angles. Microelectronic field-emission devices more generally are also attractive alternatives to semiconductor devices for many applications, being capable of high performance and being capable of fabrication from a wide range of materials with less stringent controls of material purity, but with fabrication processes and equipment similar to those used for semiconductor fabrication. A review article on the general subject of vacuum microelectronics was published in 1992: Heinz H. Busta "Vacuum Microelectronics--1992," in Journal of Micromechanics and Microengineering, Vol. 2, No. 2 (June 1992). An article by Katherine Derbyshire, "Beyond AMLCDs: Field Emission Displays?" in Solid State Technology, Vol. 37 No. 11 (November 1994) pages 55-65, summarized fabrication methods and principles of operation of some of the competing designs for field-emission devices and discussed some applications of field-emission devices to flat-panel displays. The theory of cold field emission of electrons from metals is discussed in many textbooks and monographs, including the monograph by R. O. Jenkins and W. G. Trodden, "Electron and Ion Emission From Solids" (Dover Publications, Inc., New York, N.Y., 1965), Chapter 4.